8,992 research outputs found
Neutrino Masses and Absence of Flavor Changing Interactions in the 2HDM from Gauge Principles
We propose several Two Higgs Doublet Models with the addition of an Abelian
gauge group which free the usual framework from flavor changing neutral
interactions and explain neutrino masses through the seesaw mechanism. We
discuss the kinetic and mass-mixing gripping phenomenology which encompass
several constraints coming from atomic parity violation, the muon anomalous
magnetic moment, rare meson decays, Higgs physics, LEP precision data,
neutrino-electron scattering, low energy accelerators and LHC probes.Comment: 54 pages, 10 figure
Tratamento e reciclagem de águas residuárias em sistema intensivo de produção de leite.
bitstream/item/65245/1/CT-75-Tratamento-e-reciclagem-de-aguas.pd
Phenomenological Analysis of and Elastic Scattering Data in the Impact Parameter Space
We use an almost model-independent analytical parameterization for and
elastic scattering data to analyze the eikonal, profile, and
inelastic overlap functions in the impact parameter space. Error propagation in
the fit parameters allows estimations of uncertainty regions, improving the
geometrical description of the hadron-hadron interaction. Several predictions
are shown and, in particular, the prediction for inelastic overlap
function at TeV shows the saturation of the Froissart-Martin
bound at LHC energies.Comment: 15 pages, 16 figure
Microbial biomass carbon dynamics in soil under crop-livestock-forest in northern of Mato Grosso, Brazil.
The objective was to evaluate the microbial biomass carbon (MBC) dynamics in different managements: Crop-Livestock-Forest integration systems, soybean/pasture rotation and native forest, in Brazilian Cerrado
Effective Field Theory Approach to String Gas Cosmology
We derive the 4D low energy effective field theory for a closed string gas on
a time dependent FRW background. We examine the solutions and find that
although the Brandenberger-Vafa mechanism at late times no longer leads to
radion stabilization, the radion rolls slowly enough that the scenario is still
of interest. In particular, we find a simple example of the string inspired
dark matter recently proposed by Gubser and Peebles.Comment: 19 pages, 2 figures, comments adde
A comparative analysis of the observed white dwarf cooling sequence from globular clusters
We report our study of features at the observed red end of the white dwarf
cooling sequences for three Galactic globular clusters: NGC\,6397, 47\,Tucanae
and M\,4. We use deep colour-magnitude diagrams constructed from archival
Hubble Space Telescope (ACS) to systematically investigate the blue turn at
faint magnitudes and the age determinations for each cluster. We find that the
age difference between NGC\,6397 and 47\,Tuc is 1.98\,Gyr,
consistent with the picture that metal-rich halo clusters were formed later
than metal-poor halo clusters. We self-consistently include the effect of
metallicity on the progenitor age and the initial-to-final mass relation. In
contrast with previous investigations that invoked a single white dwarf mass
for each cluster, the data shows a spread of white dwarf masses that better
reproduce the shape and location of the blue turn. This effect alone, however,
does not completely reproduce the observational data - the blue turn retains
some mystery. In this context, we discuss several other potential problems in
the models. These include possible partial mixing of H and He in the atmosphere
of white dwarf stars, the lack of a good physical description of the
collision-induced absorption process and uncertainties in the opacities at low
temperatures. The latter are already known to be significant in the description
of the cool main sequence. Additionally, we find that the present day local
mass function of NGC\,6397 is consistent with a top-heavy type, while 47\,Tuc
presents a bottom-heavy profile.Comment: Accepted for publication in MNRAS (16 pages, 19 figures
String windings in the early universe
We study string dynamics in the early universe. Our motivation is the
proposal of Brandenberger and Vafa, that string winding modes may play a key
role in decompactifying three spatial dimensions. We model the universe as a
homogeneous but anisotropic 9-torus filled with a gas of excited strings. We
adopt initial conditions which fix the dilaton and the volume of the torus, but
otherwise assume all states are equally likely. We study the evolution of the
system both analytically and numerically to determine the late-time behavior.
We find that, although dynamical evolution can indeed lead to three large
spatial dimensions, such an outcome is not statistically favored.Comment: 26 pages, LaTeX, 4 eps figure
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